Planetary Gearbox Plain Bearing Pin Profile for Uniform Lubrication
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Solution Overview
Problem
The existing planetary gear boxes with crowned plain bearing pins suffer from non-uniform plain bearing gaps and lubricating film thickness due to axial end support issues, leading to reduced load capacity and reliability.
Innovation Solution
A planetary gear box design featuring plain bearing pins with a concave contact face shape adjacent to axial ends, matching the convex curvature of the planet gear deformation, ensuring a constant plain bearing gap height and uniform lubricating film thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact face of the plain bearing pin is crowned to increase lubricating film thickness at axial ends, then the risk of metal-on-metal contact is reduced, but the planet gear is not optimally supported at the axial ends, reducing load capacity
Solution Approach 1:
The contact face is divided into different zones with different curvatures: a central zone with positive curvature (crowning) to maintain lubricating film thickness, and axial end zones with negative curvature (concave portions) to improve support and load capacity. This local differentiation allows each zone to fulfill its specific function optimally.
Solution Approach 2:
The contact face transitions from a simple crowned shape to a more complex profile incorporating concave portions at the axial ends. This curvature modification creates a surface that better adapts to the deformed shape of the planet gear during operation, improving both lubrication and load support.
2Reliability
If the contact face is crowned with a circular profile, then the lubricating film thickness is increased at axial ends, but the plain bearing gap becomes non-uniform in the axial direction due to deformation
Solution Approach 1:
Different axial zones of the contact face are given different curvature characteristics. The central portion maintains positive curvature for lubrication, while the axial end portions incorporate negative curvature to compensate for deformation-induced gap variations, achieving more uniform gap distribution overall.
Solution Approach 2:
The contact face profile is pre-shaped with concave portions at the axial ends to anticipate and compensate for the deformation that occurs during operation. This preliminary geometric adjustment ensures that the plain bearing gap remains more uniform even when the planet gear deforms under load.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the uniformity of the plain bearing gap and lubricating film thickness, improving the robustness and reliability of the planetary gear box by adapting the outer contour of the plain bearing pin to the inner contour of the planet gear during operation.
Implementation Method 1
The plain bearing pin and the planet gear form a lubricated plain bearing
Data Source
AI summary
The invention concerns a planetary gear box, which has a sun gear, a plurality of planet gears, a ring gear and a plurality of plain bearing pins. Here, a plain bearing pin is arranged in each planet gear, wherein the plain bearing pin and the planet gear form a lubricated plain bearing, and the plain bearing pin forms a crowning at its contact face, wherein the outer diameter of the contact face decreases from a maximum outer diameter towards at least one axial end of the contact face. The crowning of the contact face is configured such that the contact face is concavely shaped adjacent to at least one axial end of the contact face or to a cylindrical region adjoining the axial end.